Energy harvesting bidirectional audio interface

ABSTRACT

A payment card reader connected to an audio port of a mobile computing device may include a card interface, the card interface configured to read data from a payment card; a TRRS connector to couple the payment card reader with the mobile computing device; and an audio interface circuit coupled with the TRRS connector. The audio interface circuit may include a communication circuit configured to transmit data to and receive data from the mobile computing device via the TRRS connector and an energy harvesting circuit configured to receive an audio signal via the TRRS connector, to harvest energy from the audio signal, and to provide energy to other components of the card reader.

BACKGROUND

Mobile payment systems allow individuals and merchants to accept debit and credit cards on their smartphone, tablet, or other mobile computing device. Some mobile payment systems include a payment card reader that reads and transmits payment card information to a connected mobile computing device. These payment card readers require power to operate and transmit the payment card information to the mobile computing device. Some payment card readers include a processor to process the payment card information prior to transmitting the payment card information to the mobile computing device, which requires additional power.

Additionally, communication between the payment card reader and the mobile computing device typically requires hardware and/or software to act as a physical layer for the communication. When components of the payment card reader are updated or otherwise changed, it may be necessary to redesign the hardware and/or software that acts as the physical layer for communication between the payment card reader and the mobile computing device.

BRIEF DESCRIPTION OF THE DRAWINGS

The techniques described herein are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings, in which like reference numerals are used to refer to similar elements.

FIG. 1 illustrates a block diagram of an example payment card reader including an energy harvesting bidirectional audio interface.

FIG. 2 illustrates a block diagram of an example energy harvesting bidirectional audio interface.

FIG. 3 illustrates a block diagram of an example energy harvesting circuit.

FIG. 4 is a flow diagram of an example process for harvesting energy and receiving data using an energy harvesting bidirectional audio interface.

FIG. 5 illustrates an example architecture of a payment communication system for enabling transactions between merchants and buyers.

FIG. 6 illustrates an example block diagram of components of a merchant device.

The figures depict various embodiments of the techniques described herein for purposes of illustration only. It should be readily recognized from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the techniques described herein.

DETAILED DESCRIPTION

Example embodiments described herein include techniques and hardware arrangements for an audio interface that provides communications between a payment card reader and a mobile computing device. This audio interface may be implemented as a discrete chip (e.g., an ASIC, or the like) that acts as the physical layer between the audio port of a mobile computing device and an external digital system (e.g., a microcontroller) in the payment card reader. More specifically, the audio interface disclosed herein allows the audio port of mobile computing devices to be treated as a simple, standard serial port (e.g., UART) by an external device, such as a payment card reader, when the payment card reader is coupled with the audio port of the mobile computing device by a tip-ring-ring-sleeve (TRRS) or similar connector. On the mobile computing device, an appropriate softmodem enables the interface at the application layer.

In addition, the audio interface circuit disclosed herein may provide power to components of the payment card reader by harvesting energy from the left and/or right audio output channels of the mobile computing device, and optionally a lesser amount from the microphone channel. For example, this harvested energy can be used to power the audio interface circuit itself, local electronics of the payment card reader, and recharge a battery (or other energy storage device) on the payment card reader.

Moreover, the audio interface circuit disclosed herein can be used to provide bidirectional communication between the payment card reader and a connected mobile computing device. The payment card reader can transmit data to the mobile computing device over the microphone channel of a TRRS connector. The mobile computing device can transmit data to the payment card reader over the left and/or right audio output channel of the TRRS connector. The audio interface circuit disclosed herein allows for a combined data/energy harvesting signal to be received from the mobile computing device. For example, the audio interface circuit may receive a modulated/mixed signal (i.e., digital data with the energy harvesting signal output pattern) and demodulate the data before feeding the signal into an energy harvesting circuit.

An audio interface circuit as described herein can be used across multiple versions of payment card reader products without having to redesign or modify the communication circuitry. This allows designers to focus on unique aspects of a new product and not worry about the audio interface circuitry. Additionally, the audio interface circuit as described herein eliminates the need for specialized firmware on a per-product basis and enables the use of standard (hardware) serial ports. Further, the disclosed audio interface circuit simplifies the softmodem channel from product to product, provides energy to power local electronics, minimizes size, complexity and possibly cost of audio interface for future payment card reader products. In many cases, the energy harvesting feature of the disclosed audio interface circuit could obviate the need for a battery for payment card reader products.

FIG. 1 illustrates a block diagram of an example payment card reader 100 including an energy harvesting bidirectional audio interface. The payment card reader 100 includes an audio interface circuit 102, a microcontroller 104, a card interface 106, and a memory 108. The card reader 100 also includes an audio jack connector 110 to couple the payment card reader 100 with an audio port of a mobile computing device (not shown).

The audio interface circuit 102 acts as a physical layer between the audio port of the mobile computing device and other components of the card reader 100, for example microcontroller 104. In one embodiment, the audio interface circuit 102 may be configured to present the audio port of the mobile computing device to the components of the card reader as a simple serial port (e.g., UART). A tip-ring-ring-sleeve (TRRS) connector 110 couples the audio interface circuit 102 with the mobile computing device. The TRRS connector 110 provides the audio interface circuit 102 with four channels to communicate with the mobile computing device, a left audio channel, a right audio channel, a microphone channel, and ground. The audio interface circuit 102 may harvest energy from the left and/or right audio output channels and the microphone channel of the mobile computing device to provide power to the components of the card reader 100. While the example of FIG. 1 depicts the audio interface circuit 102 operating in the context of a payment card reader 100, it should be understood that the audio interface circuit 102 may be used to provide energy and communication to other systems as well.

Moreover, the audio interface circuit 102 can provide bidirectional communication between the payment card reader 100 and the mobile computing device. For example, the payment card reader may transmit data to the mobile computing device using the microphone channel and receive data from the mobile computing device using the left and/or right audio output channels. In some embodiments, data from the mobile computing device can be combined with a signal consumed by an energy harvesting circuit. The audio interface circuit 102 can be implemented using hardware including a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), or the like. The audio interface circuit 102 is explained in more detail below.

The microcontroller 104 is coupled to the serial port of the audio interface circuit 102. The microcontroller 104 may be configured to control the overall operation of the payment card reader 100 and to process payment card data read from a payment card using the card interface 106. Processing payment card data may include, for example, encrypting the payment card data, encoding the payment card data for transmission, or the like. The microcontroller 104 may execute instructions by performing various input/output, logical, and/or mathematical operations. The microcontroller 104 may itself comprise one or more processors or processing cores. For example, the microcontroller 104 can be implemented as one or more microprocessors, microcomputers, digital signal processors, central processing units, state machines, logic circuitries, and/or any devices that manipulate signals based on operational instructions. In some embodiments, the microcontroller 104 may be one or more hardware processors and/or logic circuits of any suitable type specifically programmed or configured to execute algorithms and processes to process and transmit payment card data. The microcontroller 104 can be configured to fetch and execute computer-readable processor-executable instructions stored in the memory 108.

The memory 108 may be or include one or more physical storage devices, which may be in the form of random access memory (RAM), read-only memory (ROM) (which may be erasable and programmable), flash memory, or other suitable type of storage device, or a combination of such devices. Instructions, executed by the microcontroller 104, for operating the payment card reader 100 may be stored as software and/or firmware in the memory 108.

The card interface 106 may be a conventional magnetic stripe reader, EMV chip reader, or other suitable type of card interface, or combination of such interfaces. For example, the card interface 106 may include a payment card slot having a read head configured to receive a magnetic stripe payment card and to facilitate reading of the magnetic stripe payment card. Similarly, the card interface 106 may include a payment card slot having components configured as a dip-slot to facilitate reading of an integrated circuit (IC) payment card, e.g., a payment card that conforms to the Europay MasterCard and Visa (EMV) global standard. In some embodiments, the card interface 106 may be configured to read both a magnetic stripe payment card and an IC payment card.

FIG. 2 illustrates a block diagram of an example energy harvesting bidirectional audio interface. The audio interface circuit 102 may include an energy harvesting circuit 202, communication circuitry 204, receiving circuitry 206, transmitting circuitry 208, power management circuitry 210, and a digital block 212. The audio interface circuit 102 can be implemented using hardware including a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC).

The energy harvesting circuit 202 is coupled with the microphone channel, the left audio channel, and the right audio channel of the TRRS connector. As described in more detail below, the energy harvesting circuit 202 converts signals received from the mobile computing device on these channels to energy to be used by components of the payment card reader 100. Additionally, the energy harvesting circuit 202 is coupled with power management circuitry 210 to provide power for operating the audio interface circuit 102. In some embodiments, power management circuitry 210 may additionally be coupled with an external power source, such as energy storage 214, to provide power to the audio interface circuit 102 in the event the energy harvesting circuit 202 is not providing power.

The communication circuitry 204 is a communication interface that implements a serial communication protocol, such as UART, USART, SPI, I2C, or the like, to be presented to components of the payment card reader 100, such as microcontroller 104. Because the communication circuitry 204 of the audio interface circuit 102 implements a standard communication protocol, upgrading and/or updating other components of the payment card reader 100 is simplified. For example, without the communication circuitry 204, custom communication circuitry coupling the components of the payment card reader 100 with the channels of the TRRS connector would have to be redesigned or verified when changes to other components of the payment card reader 100 are made.

To facilitate point-of-sale transactions, the communication circuitry 204 receives data, such as payment card information, from components of the payment card reader 100 and provides the data to transmitting circuitry 208 for transmission over the microphone channel of the TRRS connector to the mobile computing device. The communication circuitry 204 receives data from receiving circuitry 206 to transmit to components of the payment card reader 100 using the serial communication protocol. For example, the communication circuitry 204 may communicate data received from the mobile computing device to the microcontroller 104 for use in processing payment card information.

The transmitting circuitry 208 operates to convert digital data received from the microcontroller 104, or other components of the payment card reader 100, to an analog signal for transmission over the microphone line of the TRRS connector 110. In one embodiment, the transmitting circuitry 208 is a digital to analog converter. In another embodiment, the transmitting circuitry 208 includes a modulating circuit having a resistor and a transistor or switch configured to modulate an analog signal at particular frequencies to indicate digital bit values. It will be recognized that other digital to analog conversion circuits can be used for the transmitting circuitry 208.

The receiving circuitry 206 operates to receive a signal from a mobile computing device and demodulate a data signal from an energy harvesting signal carrier. In one embodiment, the receiving circuitry 206 may be implemented using known techniques for demodulating digital data from an analog carrier wave. In another embodiment, the receiving circuitry 206 may be implemented using known techniques for converting an analog signal received from the audio port of a mobile computing device to a digital signal for presentation to components of the payment card reader. In this implementation, the mobile computing device may use a digital to analog converter to encode the digital information in an analog signal before it is transmitted to the payment card reader.

In some embodiments, the audio interface circuit may optionally include a digital block 210. The digital block receives communications from the mobile computing device via the receiving circuit 206 and may be configured to control operation of components of the payment card reader 100. For example, the digital bock may be configured to power down the other components of the payment card reader to conserve energy when the mobile device is in a sleep mode or an application connected to the payment card reader is not active.

In some embodiments, the energy harvesting circuit 202 may optionally be coupled with an energy storage device 214 and in addition to powering components of the payment card reader, may charge the energy storage device 214. The energy storage device 214 may be any suitable energy storage device for storing power to be consumed later by components of the payment card reader. For example, the energy storage device 214 may be a rechargeable battery, a capacitor, a supercapacitor, or the like. While the energy storage device 214 is depicted in the example of FIG. 2 as separate from the audio interface circuit 102, in some embodiments, an energy storage device may be integrated in the audio interface circuit 102. Additionally, multiple energy storage devices (integrated with the audio interface circuit 102 or discrete components) may be present in the payment card reader 100.

FIG. 3 illustrates a block diagram of an example energy harvesting circuit 202. In one embodiment, the energy harvesting circuit 202 comprises two energy harvesting circuits; a MIC energy harvesting circuit 302 configured to harvest energy from a bias voltage on the microphone channel of the TRRS connector, and a L/R energy harvesting circuit 304 configured to harvest energy from an energy harvesting signal on the left and/or right audio channels of the TRRS connector. The MIC energy harvesting circuit 302 and the L/R energy harvesting circuit 304 are coupled by a voltage combining circuit 306 (such as a summing amplifier). In some embodiments, the MIC energy harvesting circuit 302 and the L/R energy harvesting circuit 304 can share components and may be considered a single energy harvesting circuit.

The MIC energy harvesting circuit 302 may include known or future developed circuit components and/or configurations for harvesting energy from a bias voltage. For example, the MIC energy harvesting circuit 302 may be a charge pump or transformer which manipulates the voltage provided over the microphone channel of the TRRS connector 110 to a system voltage level.

Similarly, the L/R energy harvesting circuit 304 may include known or future developed circuit components and/or configurations for harvesting energy from an oscillating signal received over the left and/or right audio channels of the TRRS connector 110. For example, the L/R energy harvesting circuit 304 may include a rectifier circuit coupled with other circuit components configured to provide a system voltage to components of the payment card reader 100. Efficiency of the L/R energy harvesting circuit 304 can be optimized through circuit design and providing an optimized signal over the left and/or right channel of the TRRS connector.

FIG. 4 is a flow diagram of one embodiment of an example process 400 for harvesting energy and receiving data using an energy harvesting bidirectional audio interface. The process described in FIG. 4 is illustrated as a collection of blocks in a logical flow diagram, which represent a sequence of operations, some or all of which can be implemented in hardware, software, or a combination thereof. The order in which the blocks are described should not be construed as a limitation. Any number of the described blocks can be combined in any order and/or in parallel to implement the process, or alternative processes, and not all of the blocks need be executed. For ease of description, the process is described with reference to the environments, architectures and systems described in the examples herein, although the process may be implemented in a wide variety of other environments, architectures and systems.

At 402, the audio interface circuit 102 may receive, via a left and/or right audio channel of the TRRS connector 110, a signal from an audio port of a mobile computing device. As described above, the signal may include an energy harvesting signal and/or a data signal generated by the mobile computing device. It will be understood that, depending on the hardware and/or software configuration of the mobile computing device, an optimized energy harvesting signal may exist for each mobile computing device. In one embodiment, software running on the mobile computing device (e.g., the merchant application 516) may select an optimum signal based on a model or hardware and software configuration of a mobile computing device. In another embodiment, the optimum signals for multiple combinations may be analyzed to determine a single signal that, on average, provides the best performance for energy harvesting across the majority of mobile computing device and payment card reader combinations.

Additionally, the amount of energy that the energy harvesting circuit 202 is able to harvest may depend on operating system settings of the mobile communication device. For example, an energy harvesting circuit 202 receiving a signal from a mobile communication device with its volume set to the maximum level will be able to harvest more energy than if the volume was set to a lower level. In one embodiment, software running on the mobile application (e.g., merchant application 516) may include a volume control feature that allows a user to manually adjust the volume of the mobile computing device to a level that provides a desired energy harvesting level. In another embodiment, the software may automatically control the volume level of the mobile computing system. In embodiments where the software is unable to control the volume level or provide an interface to the user to control the volume level, the software may provide a prompt to the user to adjust the volume of the mobile computing device to a particular level (e.g., above a threshold level).

At 404, if the signal from the audio port of the mobile computing device includes a data signal, the receiving circuit 206 may demodulate the signal to recover the data signal. The receiving circuit 206 may then pass the data signal to the communication circuit 204 for transmission to a component of the payment card reader and/or the digital block 212.

At 406, the signal drives the energy harvesting circuit 202 and at 408 provide power to operate the components of the payment card reader 100. For example, the signal may pass through a rectifier circuit and a series of capacitors, diodes, transformers, and/or other electronic components to provide a system voltage to components of the payment card reader 100. Optionally, at 410, the audio interface circuit 102 may store energy harvested by the energy harvesting circuit 202 in an energy storage device 214. As described above, the energy storage device 214 may be a component of the audio interface circuit 102 or may be a discrete component of the payment card reader 100.

FIG. 5 illustrates an example architecture of a payment communication system 500 for enabling transactions between merchants 502 and buyers 504. In the example of FIG. 5, a buyer 504 may use any of a variety of payment cards 506 when participating in a POS transaction 508 with a merchant 502. For example, a buyer 504 may typically have payment cards 506 such as credit cards, debit cards, prepaid cards, and the like, that the buyer 504 may use for conducting POS transaction 508. In some embodiments, the payment cards 508 may include one or more magnetic stripes for providing payment card and buyer information when swiped in a card reader 100. In other embodiments, other types of payment cards may be used, for example smart cards having a built in integrated circuit including a memory chip, a radio frequency identification tag, and the like.

The payment communication system 500 in the example of FIG. 5 illustrates a merchant device 510 associated with the merchant 502 that participates in the payment service provided by the service provider. As discussed elsewhere herein, the merchant device 510 may be a computing device (e.g., a mobile computing device) able to communicate with the service provider system 512, and with various other computing devices, through any suitable communication protocols, interfaces, and networks, including network 514. Further, the merchant device 510 may be any appropriate device operable to send and receive requests, messages, or other types of information over the network 514. Additionally, while only a single merchant device 510 is illustrated in the example of FIG. 5, in some implementations there may be additional merchant devices depending on the number of merchants participating in the payment service.

Each merchant device 510 may include an instance of a merchant application 516 executed on the merchant device. The merchant application 516 may provide POS functionality to enable the merchant 502 to accept payments at a POS location using the merchant device 510. In some types of businesses, the POS location may correspond to a store or other place of business of the merchant, and thus, may be a fixed location that typically does not change on a day-to-day basis. In other types of businesses, however, the POS location may change from time to time, such as in the case that the merchant 502 operates a food truck, is a street vendor, a cab driver, or has an otherwise mobile business, e.g., in the case of merchants who sell items at buyers' homes, buyers' places of business, and so forth.

Accordingly, the merchant 502 and the buyer 504 may conduct a POS transaction 508 by which the buyer 504 acquires an item or service from the merchant 502 at a POS location. The merchant application 516 on the merchant device 510 may send transaction information to the service provider system 512, e.g., as the transaction is being conducted at the POS location. In some embodiments, such as if a particular merchant device 510 is not connected to the network 514 and is therefore processing transactions offline, the transaction information may be sent in a batch at a subsequent point in time or using other suitable techniques.

The transaction information may include information regarding the time, place, and the amount of each respective transaction, information related to the item acquired, payment card information, as well as additional information, such as buyer information. For instance, the transaction information can include data stored in the payment card, e.g., magnetic stripe or integrated circuit data (cardholder name, card number, and other card information). In addition, when completing the transaction a buyer may sometimes provide a receipt email address for receiving a receipt through email. Other examples of transaction information that can be captured include detailed item information, e.g., an itemized listing of the items or services being acquired, the price being paid for each item or service, descriptors of the items or services (e.g., size, flavor, color, etc.), geolocation data indicating a geographic POS location of a particular transaction, online/offline card data, data describing the merchant, e.g., a merchant identifier, a merchant category code (MCC), any type of data that is received upon a buyer's authentication into a social network, if any, and various other types of information.

To accept electronic payments for POS transactions, the merchant 502 typically creates a merchant account on the service provider system 512 by providing information describing the merchant including, for example, merchant name, contact information (e.g., telephone numbers, the merchant's address, and one or more financial accounts to which funds collected from buyers will be deposited). This merchant information can be securely stored by the service provider, for example, as merchant information 518 in a secure database. Further, the merchant information may include a merchant profile 520 created for each merchant. The merchant profile 520 may include information about the merchant 502 and transaction information associated with transactions conducted by the merchant.

The service provider system 512 enables a service provider to provide a payment service in which merchants 502 are able to conduct POS transactions 508 with a plurality of buyers 502, such as for selling services and/or produces to the buyers 502. The service provider system 512 may include one or more servers that are configured to process secure electronic financial transactions, e.g., payment during a POS transaction 508, by communicating with the merchant device 510, card payment networks 522, and bank or other financial institution payment systems 524. The service provider system 512 includes a payment processing module 526 that receives transaction information for processing payments made through the merchant application 516. For example, the payment processing module 526 may receive transaction information, such as an amount of the transaction, and may verify that a particular payment card 506 can be used to pay for the transaction, such as by contacting a card clearinghouse of a card payment network 522. Furthermore, in some examples, the payment processing module 526 may redirect payment information for transactions to be made using payment cards 506 to a bank, or other financial institution, payment system 524. In other embodiments, the merchant device 510 may communicate directly with an appropriate card payment network 522 or bank payment system 524 for approving or denying a transaction using a particular payment card 506 for a POS transaction 508. Additional details of payment processing are discussed below.

As introduced above, the service provider system 526 may be configured to communicate with one or more systems of a card payment network 522 (e.g., MasterCard®, VISA®, or the like) over the network 514 to conduct financial transactions electronically. The service provider system 526 may also communicate with one or more bank systems 524 of one or more banks over the network 514. For example, the service provider system may communicate with an acquiring bank, a payment card issuing bank, and/or a bank maintaining buyer accounts for electronic payments.

A payment card acquiring bank may be a registered member of a card association (e.g., Visa®, MasterCard®, or the like), and may be part of a card payment network 522. A payment card issuing bank may issue payment cards 506 to buyers 502, and may pay acquiring banks for purchases made by cardholders to which the issuing bank has issued a payment card 506. Accordingly, in some embodiments, the systems of an acquiring bank may be included in the card payment network 522 and may communicate with systems of a payment card issuing bank to obtain payment. Further, in some embodiments, bank payment systems 524 may include systems associated with debit card issuing institutions, in which case, the systems of the debit card issuing institution may receive communications regarding a transaction in which the buyer uses a debit card instead of a credit card. Additionally, there may be systems of other financial institutions involved in some types of transactions or in alternative system architectures, and thus, the foregoing are merely several examples.

The network 514 can be a conventional type, wired or wireless, and may have numerous different configurations including a star configuration, token ring configuration, or other configurations. Furthermore, the network 514 may include a local area network (LAN), a wide area network (WAN) (e.g., the Internet), and/or other interconnected data paths across which multiple devices may communicate. In some embodiments, the network 514 may be a peer-to-peer network. The network 514 may also be coupled with or include portions of a telecommunications network for sending data using a variety of different communication protocols. In some embodiments, the network 514 may include Bluetooth (or Bluetooth low energy) communication networks or a cellular communications network for sending and receiving data including via short messaging service (SMS), multimedia messaging service (MMS), hypertext transfer protocol (HTTP), direct data connection, WAP, email, etc. Although the example of FIG. 5 illustrates one network 514 coupled to the merchant device, service provider system, card payment network, and bank, in practice one or more networks 514 can connect these entities.

FIG. 6 is a block diagram of components of an example merchant device 510 according to some embodiments. The merchant device 510 may be any suitable type of computing device, e.g., portable, semi-portable, semi-stationary, or stationary. Some examples of the merchant device 510 may include tablet computing devices; smart phones and mobile communication devices; laptops, netbooks and other portable computers or semi-portable computers; desktop computing devices, terminal computing devices and other semi-stationary or stationary computing devices; dedicated register devices; wearable computing devices, or other bodymounted computing devices; augmented reality devices; or other computing devices capable of sending communications and performing the functions according to the techniques described herein.

In the example of FIG. 6, the merchant device 510 includes at least one processor 602, a memory 604, one or more communication interfaces 606, and one or more input/output (I/O) devices 608. Each processor 602 may itself comprise one or more processors or processing cores. For example, the processor 602 can be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, state machines, logic circuitries, and/or any devices that manipulate signals based on operational instructions. In some embodiments, the processor 602 may be one or more hardware processors and/or logic circuits of any suitable type specifically programmed or configured to execute the algorithms and processes described herein by performing various input/output, logical, and/or mathematical operations. The processor 602 can be configured to fetch and execute computer-readable processor-executable instructions stored in the memory 604.

Depending on the configuration of the merchant device 510, the memory 604 may be an example of tangible non-transitory computer storage media and may include volatile and nonvolatile memory and/or removable and non-removable media implemented in any type of technology for storage of information such as computer-readable processor-executable instructions, data structures, program modules or other data. The computer-readable media 604 may include, but is not limited to, RAM, ROM, EEPROM, flash memory, solid-state storage, magnetic disk storage, optical storage, and/or other computer-readable media technology. Further, in some cases, the merchant device 510 may access external storage, such as RAID storage systems, storage arrays, network attached storage, storage area networks, cloud storage, or any other medium that can be used to store information and that can be accessed by the processor 602 directly or through another computing device or network. Accordingly, the memory 604 may be computer storage media able to store instructions, modules or components that may be executed by the processor 602.

The memory 604 may be used to store and maintain any number of functional components or modules that are executable by the processor 604. In some embodiments, these functional components comprise instructions or programs that are executable by the processor 602 and that, when executed, implement operational logic for performing the actions and services attributed above to the merchant device 510. Functional components of the merchant device 510 stored in the memory 604 may include the merchant application 516. In this example, the merchant application 516 includes a transaction module 610 and a dashboard module 612. For example, the transaction module 610 may present an interface, such as a payment interface to enable the merchant to conduct transactions, receive payments, and so forth, as well as for communicating with the service provider system 512 for processing payments and sending transaction information. The dashboard module 612 may further enable the merchant to manage the merchant's account, the merchant profile, merchant preferences, view saved or new pricing information, and the like. Additional functional components may include an operating system 614 for controlling and managing various functions of the merchant device 510 and for enabling basic user interactions with the merchant device 510.

In addition, the memory 604 may also store data, data structures and the like, that are used by the functional components. For example, data stored by the computer-readable media 604 may include item information 616 that includes information about the items offered by the merchant, which may include a list of items currently available from the merchant, images of the items, descriptions of the items, prices of the items, and so forth. For instance, when the merchant 502 is setting up the merchant application 516 to accept payments for particular items offered by the merchant 502, the merchant may enter the item information 616 for the particular items. Depending on the type of the merchant device 510, the computer-readable media 604 may also optionally include other functional components and data, such as other modules and data 618, which may include programs, drivers, etc., and the data used or generated by the functional components. Further, the merchant device 510 may include many other logical, programmatic and physical components, of which those described are merely examples that are related to the discussion herein.

The communication interface(s) 606 may include one or more interfaces and hardware components for enabling communication with various other devices, such as over the network(s) 514 or directly. For example, communication interface(s) 606 may enable communication through one or more of the Internet, cable networks, wireless networks (e.g., Wi-Fi) and wired networks, as well as close-range communications such as Bluetooth®, Bluetooth® low energy, and the like, as additionally enumerated elsewhere herein.

In another embodiment, the communication interface(s) 606 may include a cellular communications transceiver for sending and receiving data over a cellular communications network such as via short messaging service (SMS), multimedia messaging service (MMS), hypertext transfer protocol (HTTP), direct data connection, WAP, e-mail or another suitable type of electronic communication. The communication interface(s) 606 also provides other conventional connections to the network 206 for distribution of files and/or media objects using standard network protocols such as TCP/IP, HTTP, HTTPS and SMTP as will be understood.

The merchant device 510 may further include a display 620, which may employ any suitable display technology. For example, the display 620 may be a liquid crystal display, a plasma display, a light emitting diode display, an OLED (organic light-emitting diode) display, an electronic paper display, or any other suitable type of display able to present digital content thereon. In some embodiments, the display 620 may have a touch sensor associated with the display 620 to provide a touchscreen display configured to receive touch inputs for enabling interaction with a graphical user interface presented on the display 620. Accordingly, embodiments described herein are not limited to any particular display technology. Alternatively, in some embodiments, the merchant device 510 may not include the display 620, and information may be presented by other means, such as aurally.

The merchant device 510 may further include the one or more I/O devices 608. The I/O devices 608 may include speakers, a microphone, a camera, and various user controls (e.g., buttons, a joystick, a keyboard, a keypad, etc.), a haptic output device, and so forth.

In addition, the merchant device 510 may include or may be connectable to a payment card reader 100. In some embodiments, the payment card reader 100 may plug in to a port in the merchant device, such as a microphone/headphone port (as described above), a data port, or other suitable port. The payment card reader 100 may include a card interface for reading a magnetic stripe or an integrated circuit of a payment card 506, and further may include encryption technology for encrypting the information read from the payment card 506. Alternatively, numerous other types of payment card readers 100 may be employed with the merchant devices 510 herein, depending on the type and configuration of the merchant device 510.

As used here, the term “payment card” refers to a payment mechanism which includes a debit card, a conventional credit card, “smartcards” that have embedded integrated circuit chips (e.g., Europay-MasterCard-Visa (EMV) cards), or any wallet-size card which functions as a combination of any of these payment mechanisms.

Other components included in the merchant device 510 may include various types of sensors (not shown), which may include a GPS device, an accelerometer, gyroscope, compass, proximity sensor, and the like. Additionally, the merchant device 510 may include various other components that are not shown, examples of which include removable storage, a power source, such as a battery and power control unit, and so forth.

A payment card reader including an energy harvesting bidirectional audio interface has been described. In the above description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the techniques introduced herein. It will be apparent, however, to one skilled in the art that the techniques can be practiced without these specific details. In other instances, structures and devices are shown in block diagram form in order to avoid obscuring the description and for ease of understanding. For example, the techniques are described in one embodiment above primarily with reference to software and particular hardware. However, the techniques may be implemented using any type of computing system that can receive data and commands, and present information as part of any peripheral device providing services.

Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the description. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.

Some portions of the detailed descriptions described above are presented in terms of algorithms and symbolic representations of operations on data bits within a computer memory. These algorithmic descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. An algorithm is here, and generally, conceived to be a self-consistent sequence of steps leading to a desired result. The steps are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers or the like.

It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise as apparent from the following discussion, it is appreciated that throughout the description, discussions utilizing terms such as “processing” or “computing” or “calculating” or “determining” or “displaying” or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system's registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices.

The present specification also relates to an apparatus for performing the operations herein. This apparatus may be specially constructed for the required purposes, or it may comprise a general-purpose computer selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a computer readable storage medium, such as, but is not limited to, any type of disk including floppy disks, optical disks, CD-ROMs, and magnetic disks, read-only memories (ROMs), random access memories (RAMs), EPROMs, EEPROMs, magnetic or optical cards, flash memories including USB keys with non-volatile memory or any type of media suitable for storing electronic instructions, each coupled to a computer system bus.

The specification can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment containing both hardware and software elements. In one embodiment, the specification is implemented in software, which includes but is not limited to firmware, resident software, microcode, etc.

Furthermore, the description can take the form of a computer program product accessible from a computer-usable or computer-readable medium providing program code for use by or in connection with a computer or any instruction execution system. For the purposes of this description, a computer-usable or computer readable medium can be any apparatus that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.

A data processing system suitable for storing and/or executing program code will include at least one processor coupled directly or indirectly to memory elements through a system bus. The memory elements can include local memory employed during actual execution of the program code, bulk storage, and cache memories which provide temporary storage of at least some program code in order to reduce the number of times code must be retrieved from bulk storage during execution.

Input/output (I/O) devices (including but not limited to keyboards, displays, pointing devices, etc.) can be coupled to the system either directly or through intervening I/O controllers.

Network adapters may also be coupled to the system to enable the data processing system to become coupled to other data processing systems or remote printers or storage devices through intervening private or public networks. Modems, cable modems and Ethernet cards are just a few of the currently available types of network adapters.

Finally, the algorithms and displays presented herein are not inherently related to any particular computer or other apparatus. Various general-purpose systems may be used with programs in accordance with the teachings herein, or it may prove convenient to construct more specialized apparatus to perform the required method steps. The required structure for a variety of these systems will appear from the description below. In addition, the specification is not described with reference to any particular programming language. It will be appreciated that a variety of programming languages may be used to implement the teachings of the specification as described herein.

The foregoing description of the embodiments has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the techniques to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the embodiments be limited not by this detailed description, but rather by the claims of this application. As will be understood by those familiar with the art, the examples described herein may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Likewise, the particular naming and division of the modules, routines, features, attributes, methodologies and other aspects are not mandatory or significant, and the mechanisms that implement the techniques or features may have different names, divisions and/or formats. Furthermore, as will be apparent to one of ordinary skill in the relevant art, the modules, routines, features, attributes, methodologies and other aspects of the techniques can be implemented as software, hardware, firmware or any combination of the three. Also, wherever a component, an example of which is a module, is implemented as software, the component can be implemented as a standalone program, as part of a larger program, as a plurality of separate programs, as a statically or dynamically linked library, as a kernel loadable module, as a device driver, known to those of ordinary skill in the art of computer programming. Additionally, the techniques are in no way limited to implementation in any specific programming language, or for any specific operating system or environment. Accordingly, the specification is intended to be illustrative, but not limiting, of the scope of the claims, which are set forth below. 

What is claimed is:
 1. A mobile point-of-sale (POS) terminal for processing a financial transaction between a buyer and a merchant, the mobile POS terminal comprising: a mobile computing device having a tip-ring-ring-sleeve (TRRS) jack, the mobile computing device configured to run a register application, wherein the register application is configured to receive payment data from the buyer via a payment card reader for facilitating a transfer of funds from the buyer to the merchant; and the payment card reader coupled with the mobile computing device via the TRRS jack, the payment card reader comprising: a card interface configured to read the payment data from a payment card; a processor coupled with the card interface, the processor configured to process the payment data from the payment card to determine financial information associated with the buyer that is used by the register application to facilitate the transfer of funds from the buyer to the merchant; a TRRS connector; and an audio interface application-specific integrated circuit (ASIC) coupled with the TRRS connector, the audio interface ASIC comprising: a communication circuit configured to convey one or more communications between the payment card reader and the mobile computing device via the TRRS connector; and an energy harvesting circuit configured to receive an audio signal via an audio contact of the TRRS connector and a bias voltage via a microphone contact of the TRRS connector, to harvest energy from the audio signal and the bias voltage, and to provide the harvested energy to the card interface and the processor.
 2. The mobile POS terminal of claim 1, wherein the audio interface ASIC further comprises a demodulator configured to demodulate a data signal from the audio signal.
 3. The mobile POS terminal of claim 1, further comprising an energy storage device coupled with the energy harvesting circuit, the energy storage device configured to store the harvested energy harvested by the energy harvesting circuit.
 4. The mobile POS terminal of claim 1, wherein the audio signal comprises a first signal received via a left channel audio contact of the TRRS connector and a second signal received via a right channel audio contact of the TRRS connector.
 5. A payment card reader comprising: a card interface configured to read payment data from a payment card; a tip-ring-ring-sleeve (TRRS) connector to couple the payment card reader with a mobile computing device; and an audio interface circuit coupled with the TRRS connector, the audio interface circuit comprising: a communication circuit configured to convey one or more communications between the payment card reader and the mobile computing device via the TRRS connector; and an energy harvesting circuit configured to receive an audio signal via the TRRS connector, to harvest energy from the audio signal, and to provide the harvested energy to the card interface of the payment card reader.
 6. The payment card reader of claim 5, further comprising a processor coupled with the card interface and the audio interface circuit, the processor configured to process the payment data from the payment card to determine financial information associated with a buyer and the audio interface circuit configured to transmit the financial information associated with the buyer to the mobile computing device.
 7. The payment card reader of claim 5, wherein the energy harvesting circuit comprises a first circuit coupled with an audio contact of the TRRS connector, the first circuit configured to harvest energy from the audio signal received via the audio contact.
 8. The payment card reader of claim 7, wherein the energy harvesting circuit comprises a second circuit coupled with a microphone contact of the TRRS connector, the second circuit configured to harvest energy from a bias voltage received via the microphone contact.
 9. The payment card reader of claim 5, wherein the audio interface circuit further comprises a demodulator configured to demodulate a data signal from the audio signal.
 10. The payment card reader of claim 5, further comprising an energy storage device coupled with the energy harvesting circuit, the energy storage device configured to store the harvested energy harvested by the energy harvesting circuit.
 11. The payment card reader of claim 5, wherein the card interface is configured to read the payment data from a magnetic strip of the payment card.
 12. The payment card reader of claim 5, wherein the card interface is configured to read the payment data from an integrated circuit of the payment card.
 13. The payment card reader of claim 5, wherein the audio signal comprises a first signal received via a left channel audio contact of the TRRS connector and a second signal received via a right channel audio contact of the TRRS connector.
 14. A method comprising: receiving, at an audio interface circuit of a payment card reader, an audio signal from a mobile computing device via an audio contact of a tip-ring-ring-sleeve (TRRS) connector; driving an energy harvesting circuit using the audio signal, wherein the energy harvesting circuit is configured to harvest energy from the audio signal and to provide the harvested energy to a card interface of the payment card reader; reading payment card information from a payment card using the card interface of the payment card reader; receiving, at the audio interface circuit, the payment card information from the payment card reader; and transmitting, using the audio interface circuit, the payment card information to the mobile computing device via the TRRS connector.
 15. The method of claim 14, further comprising processing the payment card information to determine financial information associated with a buyer, wherein transmitting the payment card information comprises transmitting the financial information associated with the buyer.
 16. The method of claim 14, further comprising: receiving, from the mobile computing device, a bias voltage via a microphone contact of the TRRS connector; and driving a second energy harvesting circuit using the bias voltage, wherein the second energy harvesting circuit is configured to harvest secondary energy from the bias voltage and to provide the harvested secondary energy to the card interface of the payment card reader.
 17. The method of claim 14, further comprising demodulating a data signal from the audio signal.
 18. The method of claim 14, further comprising storing energy harvested by the energy harvesting circuit.
 19. The method of claim 14, wherein the card interface is configured to read the payment card information from a magnetic strip of the payment card.
 20. The method of claim 14, wherein the card interface is configured to read the payment card information from an integrated circuit of the payment card.
 21. The method of claim 14, wherein receiving the audio signal comprises: receiving a first signal via a left channel audio contact of the TRRS connector; and receiving a second signal via a right channel audio contact of the TRRS connector. 